This invention relates to tracking systems for radar guided homing missiles. While it is applicable to systems having fixed antennas with electronic beam steering, it is primarily intended for partially strapdown systems, i.e., systems in which a gimbal mounted antenna is stabilised in space by means of gyroscopes strapped down, i.e., fixed, to the body of the missile, as compared to the more conventional gimbal systems where gyros are mounted directly on the antenna.